Process for making 1,3,6-octatrienes by dimerization

ABSTRACT

Catalytic process for dimerizing substituted 1,3-butadienes in presence of zirconium and vanadium catalysts at elevated temperatures, with or without solvents and co-catalysts such as phosphines.

' United States Patent Ploner Nov. 4, 1975 I PROCESS FOR MAKING 3,372,206 3/1968 Pruett et al. 260/666 B 1 3 6 OCTATR]ENES BY DIMERIZATION 3,444,258 5/1969 Kohnle et a] 260/677 R 3,457,319 7/1969 Olechowski et al 260/677 R Inventor: -J 'g n Grelfensee, 3,641,175 2/1972 Wilke et al 260/677 R Switzerland 3,689,585 9/1972 gn ez iv o por tion Clifton, NJ. 3,708,551 l/l973 Klttleman et al. 260/683 D [22] Filed: Jan. 30, 1974 FOREIGN PATENTS OR APPLICATIONS 2 O 6 7 R [21] Appl NO: 438,084 2,063,038 7/1971 Germany 6 7 Primary Examiner-Delbert E. Gantz Foreign Appllcatlon Prlonty Data Assistant Examiner-Juanita M. Nelson Feb. 2, 1973 Switzerland 1553/73 Attorney, Agent, orFirm-Thomas Cifelli, Jr.

[52] US. Cl. 260/677 R; 260/680 B; 260/666 B 51 Int. 01. c07c 11/00; c07c 11/21 ABSTRACT 5 Fleld of Search 260/677 666 680 Catalytic process for dimerizing substituted 1,3-

260/680 B butadienes in presence of zirconium and vanadium catalysts at elevated temperatures, with or without sol- [56] References Clted vents and co-catalysts such as phosphines.

UNITED STATES PATENTS 3,219,716 ll/l965 Wittenberg et al. 260/666 R 9 Chums D'awmgs 1 PROCESS FOR MAKING 1,3,6-OCTATRIENES BY DIMERIZATION FIELD OF THE INVENTION This invention relates to the field of organic chemistry.

SUMMARY OF THE INVENTION The unsaturated compounds obtained according to the present process have the following general formula wherein R and R represent a lower alkyl or lower alkenyl group. According to the present invention, the unsaturated compounds of formula I hereinbefore are manufactured by treating a compound of the general formula wherein R has the significance given earlier, or mixtures of compounds of formula II with a catalyst of the formula (R SiO),,Zr or (R SiO) VO and a compound of the formula AIR X, in which X represents a halogen atom and R represents a lower alkyl, cycloalkyl, phenyl or phenyl-(lower alkyl) group and in which the R-symbols can be different from one another.

PRIOR ART DESCRIPTION OF THE PREFERRED EMBODIMENTS As used in this description and in the accompanying claims, the term lower means groups containing up to 7 carbon atoms. Examples of lower alkyl groups are the methyl, ethyl, propyl and butyl groups as well as isomers of the latter two. A preferred lower alkenyl group is the 4-methyl-penten-3-yl group. Particularly preferred compounds of formula II are isoprene, mycrene, B-farnesene, methyl butadiene and propyl butadiene.

The process provided by the present invention can be carried out in the presence of, or in the absence of, a solvent. Aliphatic or aromatic hydrocarbons may be used as the solvent. The process is conveniently carried out at a temperature between 50C and 200C, preferably at l20C. Furthermore, a phosphine, a phosphite, a tertiary amine or an ether can be added to the reaction mixture as a co-catalyst. The addition of such a co-catalyst is preferred when a vanadium catalyst is used in the process. Specific examples of such cocatalysts are trimethylphosphine, triethylphosphine, tripropylphosphine, tributylphosphine, triphenylphosphine and tricresylphosphine, triphenylphosphite, tetrahydrofuran, triethylamine and 2,2'-bipyridyl.

In the present process there are conveniently used, per mol of diene of formula II, 01-50 mmol of zirconium or vanadium catalyst and up to 10 mol of cocatalyst per mol of zirconium or vanadium catalyst. The ratio zirconium or vanadium catalyst: aluminum compound conveniently amounts to 1:1 to 1:20.

Examples of zirconium and vanadium catalysts which may find use in the process of the present invention are I a)a]-4; I 2 s)a]4; 6 5)3]4; W (CH3)3]3; 6 5)3]3; 6 11)3]3 and 6 4 3)3]3- Examples of compounds of the formula AlR X are di-ethyl-aluminum chloride; di-propyl-aluminum chloride; di-butyl-aluminum chloride; di-isobutyl-aluminum chloride; di-octyl-aluminum chloride, di-ethyl aluminum bromide and mixtures of one mole aluminum chloride and two moles triethyl aluminum or two moles triisobutyl aluminum; and one mole of aluminum bror'nide and two moles of triisobutyl aluminum.

The zirconium and vanadium compounds which are used as the catalysts, insofar as they are not known, can be prepared in analogy to processes known per se (see J. Chem. Soc. 1959, 3404).

The following Examples illustrate the present invention:

EXAMPLE 1 4.8 g of tetrakis-(triphenyl-silyloxy)-zirconium, 2.1 g of triphenylphosphine, 50 ml of benzene, 50 ml of distilled isoprene and 4.8 g of diethylaluminum chloride were added to a 300 ml autoclave under an argon atmosphere. The autoclave was closed and the mixture stirred for 2 hours at C. Thereafter, the organic products were distilled off from the catalyst at 20-l00C/0.1 mm Hg into a cooled receiver. After removal of the benzene at 30C/10 mm Hg, there remained behind 58 g of a colourless oil, gas-chromatographic analysis (phase: Apiezon L) of which yielded the following results:

82 percent 2,6-dimethyl-1,3,6-octatriene,

6 percent 2,7-dimethyl-l ,3,6-octatriene,

2 percent cyclic isoprene dimer,

10 percent isoprene trimer.

The 2,6-dimethyl-1,3,6-octatriene (n 1.4806) was obtained in pure form by repeated distillation on a spinning-band column at 53C/l0 Torr. The catalyst remaining behind after the distillation can be re-used immediately after the addition of diethylaluminium chloride.

EXAMPLE 2 68 g of distilled isoprene, 13.6 g of myrcene (97 percent), 4.8 g of tetrakis-(triphenyl-silyloxy)-zirconium, 2.1 g of triphenylphosphine, 100 ml of absolute benzene and 4.8 g of diethylaluminium chloride were placed in a 300 ml autoclave. The diethylaluminium chloride was added finally under argon. After stirring for 2 hours at 100C, the autoclave was opened and the product added to 200 g of ice and 50 ml of concen- 3 trated hydrochloric acid. After extraction with hexane, neutralisation, drying and removal of the solvent, there were obtained 64.5 g of a crude product having the fol- 5.0% 2,7-dimethyl-l,3,6-

octatriene 2.0% isoprene trimer mm Hg) 15 The C -hydrocarbon can be obtained in pure form by distillation on a spinning-band column at 124C/ 10 mm Hg; n 1.4962.

EXAMPLE 3 0.892 g of tris-(triphenylsilyl)-orthovanadate, 0.5 ml of tetrahydrofuran, 50 ml of isoprene and 3.6 ml of diethyl aluminum chloride were added to a 100 ml autoclave under an argon atmosphere. The autoclave was closed and the mixture stirred for 2 hours at 100C. After cooling the reaction product was added to 50 g of ice and extracted with hexane. After removal of the solvent there were obtained 19.5 g of a colourless oil consisting of 46 percent 2,6-dimethyl-1,3,6-octatriene 8 percent 2,7-dimethyl-1,3,6-octatriene 13 percent cyclic isoprene dimer 33 percent isoprene trimer and polymes.

The unreacted isoprene (14 g) was recovered from the solvent fraction by distillation.

EXAMPLE 4 0.334 g of tris-(trimethylsilyl)-orthovanadate, 0.1 ml of triethylamine, 50 ml of isoprene, 50 ml of hexane and 1.8 ml of diethyl aluminum chloride were reacted for 3 hours in analogy to the procedure of Example 3. There was obtained 59 percent 2,6-dimethyl-l,3,6- octatriene and 10 percent 2,7 dimethyl-l,3,6-octatriene.

What we claim is:

1. A process for the manufacture of unsaturated compounds of the general formula wherein R and R represent a lower alkyl or lower alkenyl group, which process comprises reacting a compound of the general formula wherein R has the significance given earlier in this claim,

or mixtures of compounds of formula II at temperatures within the range from 50C. to 200C., with a material selected from the group consisting of a compound of the formula (R SiO) Zr and (R SiO) VO and a compound of the formula AIR X, in which X represent a halogen atom and R is selected from the group consisting of a lower alkyl, cycloalkyl, phenyl and a phenyl-(lower alkyl) group and in which the R-symbols can be different from one another, lower meaning a group having up to 7 carbon atoms.

2. A process according to claim 1, wherein a phosphine, a phosphite, a tertiary amine or an ether is added to the reaction mixture as a co-catalyst in amounts up to 10 mol per mol of catalyst.

3. A process according to claim 1, wherein tetrakis- (triphenyl-silyloxy)-zirconium is used as the zirconium compound.

4. A process according to claim 1, wherein diethylaluminum chloride is used as the aluminum compound.

5. A process according to claim 1, wherein triphenylphosphine is added to the reaction mixture.

6. A process according to claim 1, wherein the ratio of zirconium or vanadium catalystzaluminum compound amounts to 1:1 to 1:20.

7. A process according to claim 1, wherein 0.1-50 mmol of zirconium or vanadium catalyst is used per mol of diene of formula II.

8. A process according to claim 2, wherein isoprene is the compound of formula II, tetrakis-(triphenylsilyloxy)-zirconium 'is the catalyst, diethylaluminum chloride is used as the aluminum compound, triphenylphosphine is used as the co-catalyst, and the reaction is conducted in an autoclave under an argon atmosphere at a temperature of about C.

9. A process according to claim 2, wherein a mixture of isoprene and myrcene is reacted in an autoclave in the presence of tetrakis-(triphenyl-silyloxy)-zirconium, triphenyl-phosphine and diethylaluminum chloride under an argon atmosphere at a temperature of about 100C.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Inv n Klaus-Jurzen Ploner It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

1 should read Column 2, line 19, "ovLb Si(CH 3 3 3 --ov[osi (cH(cH 3 Signed and Sealed this A ttes t:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner of'Patents and Trademarks 

1. A PROCESS FOR THE MANUFACTURE OF UNSATURATED COMPOUNDS OF THE GENERAL FORMULA
 2. A process according to claim 1, wherein a phosphine, a phosphite, a tertiary amine or an ether is added to the reaction mixture as a co-catalyst in amounts up to 10 mol per mol of catalyst.
 3. A process according to claim 1, wherein tetrakis-(triphenyl-silyloxy)-zirconium is used as the zirconium compound.
 4. A process according to claim 1, wherein diethylaluminum chloride is used as the aluminum compound.
 5. A process according to claim 1, wherein triphenylphosphine is added to the reaction mixture.
 6. A process according to claim 1, wherein the ratio of zirconium or vanadium catalyst:aluminum compound amounts to 1:1 to 1:20.
 7. A process according to claim 1, wherein 0.1-50 mmol of zirconium or vanadium catalyst is used per mol of diene of formula II.
 8. A process according to claim 2, wherein isoprene is the compound of formula II, tetrakis-(triphenyl-silyloxy)-zirconium is the catalyst, diethylaluminum chloride is used as the aluminum compound, triphenylphosphine is used as the co-catalyst, and the reaction is conducted in an autoclave under an argon atmosphere at a temperature of about 100*C.
 9. A process according to claim 2, wherein a mixture of isoprene and myrcene is reacted in an autoclave in the presence of tetrakis-(triphenyl-silyloxy)-zirconium, triphenyl-phosphine and diethylaluminum chloride under an argon atmosphere at a temperature of about 100*C. 